access icon free Theoretical analysis on the relationship between left ventricular energetic efficiency and acute infarct size

© The Institution of Engineering and Technology
Received 01/11/2011, Accepted 17/08/2012, Revised 29/02/2012, Published

Energetic efficiency is an important indicator of cardiac function in acute myocardial infarction. However, the relationship between cardiac energetic efficiency and infarct size is not perfectly elucidated. In this study, the relationship is analysed by means of simulation using a theoretical model of the guinea pig left ventricle. In simulation with varied ratios of infarct area, pressure–volume area (PVA), which is an index of total mechanical energy by ventricular contraction, and myocardial oxygen consumption (MVO2) are calculated for each infarct ratio. Then, change of PVA when MVO2 alters (PVA/MVO2) as a well-known index of energy conversion efficiency is evaluated. In addition, PVA/VO2, which represents a ratio of PVA change to alteration of mean oxygen consumption of myocytes except for infarct myocytes, is introduced as an index for real energetic efficiency. In simulation results, PVA/MVO2 increases but PVA/VO2 decreases as infarct area expands, because with expansion of infarct area PVA decreases but VO2 remains almost unchanged because of larger shortening of myocytes. This implies that the enlargement of shortening of noninfarcted myocyte to compensate for depression of cardiac output is a potential cause of myocardial remodelling.

Inspec keywords: blood vessels; cellular biophysics; haemodynamics; cardiology; physiological models; oxygen; muscle

Other keywords: energetic efficiency index; infarct myocytes; cardiac output; ventricular contraction; total mechanical energy; acute infarct size; cardiac function; cardiac energetic efficiency; theoretical analysis; myocardial remodelling; guinea pig left ventricle; myocyte mean oxygen consumption; noninfarcted myocyte shortening enlargement; acute myocardial infarction; energy conversion efficiency; pressure-volume area; left ventricular energetic efficiency; myocardial oxygen consumption

Subjects: Haemodynamics, pneumodynamics; Cellular biophysics; External and internal data communications, nerve conduction and synaptic transmission; Rheology of body fluids

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